Method for Producing Patterned Plate

ABSTRACT

A device producing a patterned plate includes a die and an electromagnetic actuator. The die includes a patterned surface with a pattern formed thereon and a fracturing part. The tubular work piece is disposed between the die and the electromagnetic actuator such that walls of the tubular work piece correspond to walls of the die. When the electromagnetic actuator is supplied with a current pulse, an eddy current is induced in the tubular work piece, generating a repulsive force between the electromagnetic actuator and the tubular work piece. Therefore, the tubular work piece impacts the die, and a forming surface of the tubular work piece is deformed against the patterned surface and the fracturing part, thus replicating the pattern of the patterned surface onto the forming surface. At the same time, the tubular work piece is fractured at the position corresponding to the fracturing part.

CROSS REFERENCE

The present application is a division of U.S. patent application Ser.No. 12/345,808 filed on Dec. 30, 2008.

BACKGROUND

1. Field of the Invention

The present invention relates to a device and a method thereof forproducing a patterned plate from a tubular work piece, and inparticular, the present invention relates to a device and a methodthereof which employs an electromagnetic forming process for producing apatterned plate from a tubular work piece.

2. Description of the Related Art

U.S. Pat. No. 7,076,981 discloses a method of forming a bipolar platethrough an electromagnetic forming process. A metal plate is used in theprocess. When an external force is exerted upon the metal plate, it ispressed against a conductive frame, and an induced Eddy current isproduced. The problem of spark discharge often arises during the pulsingof the induced current, causing safety and yield rate concerns duringmass production.

U.S. Pat. No. 7,178,374 discloses a method of forming a bipolar platethrough a press forming process involving designing a die, such that thestress distribution of the plate material is controlled to produce aplate with a uniform thickness. This method is intended to reduce thecurving effect caused by the residual stress in the work-pieces, and toenhance the overall formation process. However, it is still possible forsome residual stress to reside in the work-pieces.

U.S. Pat. No. 6,938,449 discloses a simplified hydraulic forming devicecomprising an upper die, which is able to move upward and downward, anda fixed bottom die filled with a liquid. The liquid inside the die issealed by a plate and a blank holder. The pressure of the fluid isincreased by pressing down the upper die toward an accommodating sectionof the fluid, whereby a part of the plate is deformed. However, thehydraulic forming process is not suitable for producing a fine pattern.

Therefore, an improved device and a method thereof for producing apattern is desired to overcome the above-mentioned shortcomings.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a device and amethod thereof for producing a patterned plate efficiently.

Another objective of the present invention is to provide a device havinga quasi-hydrostatic effect and a method thereof for producing apatterned plate.

A third objective of the present invention is to provide a device and amethod thereof for producing a patterned plate, which prevent theproblem of spark discharge.

In order to achieve the above-mentioned objectives, the presentinvention provides a device for producing a patterned plate from atubular work piece. The device comprises a die and an electromagneticactuator. Walls of the die comprise at least one patterned surface witha pattern formed thereon and at least one fracturing part. The tubularwork piece is disposed between the die and the electromagnetic actuator.Walls of the tubular work piece correspond to the walls of the die, anda forming surface of the tubular work piece corresponds to the patternedsurface of the die. When the electromagnetic actuator is supplied with acurrent pulse, a current is induced in the tubular work piece, and arepulsive force is generated between the electromagnetic actuator andthe tubular work piece. The repulsive force causes the walls of thetubular work piece to impact the walls of the die and deforms theforming surface against the patterned surface such that the formingsurface replicates the pattern of the patterned surface. Meanwhile, thetubular work piece is fractured at the position corresponding to thefracturing part.

Please note that the electromagnetic actuator can be either inside thedie or outside the die.

To achieve the above-mentioned objectives, the present invention alsoprovides a method for producing a patterned plate from a tubular workpiece. The method comprises the following steps: disposing the tubularwork piece between a die and an electromagnetic actuator, with walls ofthe tubular work piece corresponding to walls of the die and with aforming surface of the tubular work piece corresponding to a patternedsurface of the die; supplying a current pulse to the electromagneticactuator to induce a current in the tubular work piece, thus generatinga repulsive force between the electromagnetic actuator and the tubularwork piece, with the repulsive force causing the walls of the tubularwork piece to impact on the walls of the die and deforming the formingsurface of the tubular work piece against the corresponding patternedsurface of the die such that the forming surface takes on a pattern ofthe patterned surface; and cutting the patterned forming surface andseparating it from the tubular work piece to form a plate.

Please note that before placing the tubular work piece between the dieand the electromagnetic actuator, a further step is needed: placing thedie inside the electromagnetic actuator or placing the electromagneticactuator inside the die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an assembly view of the first embodiment of apattern-producing device of the present invention.

FIG. 2 shows a cross-sectional view of the first embodiment of thepattern-producing device of the present invention.

FIG. 3 shows a fracturing part of the pattern-producing device of thepresent invention.

FIG. 4 shows another fracturing part of the present invention.

FIG. 5 shows a cross-sectional view of a second embodiment of thepattern-producing device of the present invention.

FIG. 6 is a flow chart showing the process of producing a pattern of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The advantages and innovative features of the invention will become moreapparent from the following preferred embodiments.

Refer to FIG. 1 to FIG. 4 for the first embodiment of apattern-producing device in accordance with the present invention. Asshown in FIG. 1, a pattern-producing device 1 comprises a die 30, anelectromagnetic actuator 40 and a magnetic concentrator 50. The die 30is a tube-shape die, and inner walls of the die 30 comprise a patternedsurface 31 with a pattern 311 formed thereon as well as a fracturingpart 32. The dimension of the pattern 311 ranges from 1 μm to 10 mm, butthe present invention is not limited only to this specification. Thefracturing part 32 can either be an indented groove 321 (as shown inFIG. 3) or a protruding part 322 (as shown in FIG. 4), but the presentinvention is not limited only to these shapes. In the first embodiment,the electromagnetic actuator 40 is made of an electromagnetic coil.

As shown in FIG. 1 and FIG. 2, the electromagnetic actuator 40 of thefirst embodiment is positioned inside the die 30. Walls of the tubularwork piece 20 comprise at least one forming surface 21. The tubular workpiece 20 is disposed between the die 30 and the electromagnetic actuator40, the walls of the tubular work piece 20 correspond to the inner wallsof the die 30, and the forming surface 21 corresponds to the patternedsurface 31. When the electromagnetic actuator 40 is supplied with acurrent pulse, the current pulse induces a current in the tubular workpiece 20. A repulsive force is consequently generated between theelectromagnetic actuator 40 and the tubular work piece 20. The repulsiveforce then causes the walls of the tubular work piece 20 to move rapidlytowards the inner walls of the die 30 and to impact on the patternedsurface 31 as well as the fracturing part 32. Therefore, the formingsurface 21 of the tubular work piece 20 is deformed against and takes onthe pattern 311 of the patterned surface 31. Meanwhile, tubular workpiece 20 is fractured at the position corresponding to the fracturingpart 32. The pattern 311 is replicated onto the tubular work piece 20 ata high velocity through a quasi-hydrostatic pressure. Therefore, it hascharacteristics such as high malleability and fewer spring-backquantities, and creases are prevented from forming. Unlike related priorarts, the conductive frame is not required, and no pressing device isneeded to press against the tubular work piece 20 physically while thepattern forming process is performed, thus resolving the problem ofspark discharge.

In one of the embodiments, the thickness of the walls of the tubularwork piece 20 is substantially between 0.1 mm to 0.4 mm, but the presentinvention is not limited only to this thickness. The tubular work piece20 can be made of a metal or any compound material that has a magneticconducting property. Again, the present invention is not limited tothese materials. Any materials that can induce eddy currents when theelectromagnetic actuator 40 is supplied with a current are said to fallwithin the scope of the present invention. The material of the tubularwork piece 20 is substantially selected from aluminum, copper, ferrum,aurum, silver, titanium or any alloy combination thereof

In one of the embodiments, the tubular work piece 20 can be deformed ata speed exceeding 300 m/sec, replicating a pattern in 10 μsec to 100μsec. However, the present invention is not restricted to thesespecifications. The aforementioned repulsive force is a non-contactforce so the tubular work piece 20 receives an evenly-distributed forceand impacts to the patterned surface 31 instantaneously. Thisquasi-hydrostatic shaping force minimizes the residual stress of thetubular work piece 20.

In one of the embodiments, as shown in FIG. 2, the shapes of the tubularwork piece 20 and the die 30 are both rectangular, but the presentinvention is not restricted to this shape. For example, they can also becircular, triangular, or shaped of other polygons. Although the tubularwork piece 20 and the die 30 are both rectangular in this embodiment,the present invention is not limited to this arrangement. For example,the shape of the tubular work piece 20 can be circular, and the die 30can be other polygons.

In one of the embodiments, the magnetic concentrator 50 is made ofcopper, but the present invention is not limited only to this material.The magnetic concentrator 50 can also be made of other conductivematerials. When the size of the electromagnetic actuator 40 is muchsmaller than the internal diameter of the die 30, the magneticconcentrator 50 can be positioned between the tubular work piece 20 andthe electromagnetic actuator 40 (as shown in FIG. 1 and FIG. 2) to aidinduction between the tubular work piece 20 and the electromagneticactuator 40.

Next, refer to FIG. 5 for the second embodiment of the pattern-producingdevice 1′ in accordance with the present invention. The secondembodiment is different from the first embodiment in that the die 30 ispillar-shaped and in that external walls of the die 30 comprise at leastone patterned surface 31 with a pattern 311 formed thereon and at leastone fracturing part 32. The die 30 is positioned inside theelectromagnetic actuator 40. The tubular work piece 20 is disposedbetween the die 30 and the electromagnetic actuator 40. The walls of thetubular work piece 20 correspond to the external walls of the die 30,and the forming surface 21 of the tubular work piece 20 corresponds tothe patterned surface 31 of the die 30. When the electromagneticactuator 40 is supplied with a current pulse, it induces a current inthe tubular work piece 20. A repulsive force is consequently generatedbetween the electromagnetic actuator 40 and the tubular work piece 20.By the repulsive force, the walls of the tubular work piece 20 moverapidly towards the external walls of the die 30 and impact on thepatterned surface 31 as well as the fracturing part 32. Therefore theforming surface 21 of the tubular work piece 20 is deformed and takes onthe pattern 311 of the patterned surface 31 of the die 30. At the sametime, the tubular work piece 20 is fractured at the positioncorresponding to the fracturing part 32.

As shown in FIG. 5, the magnetic concentrator 50 of the embodiment ispositioned between the tubular work piece 20 and the electromagneticactuator 40 to aid induction. In this embodiment, the magneticconcentrator 50 and the electromagnetic actuator 40 are bothcylindrical, but the present invention is not limited only to this shapearrangement.

The present invention also presents a method for producing a patternonto a plate. Refer to FIG. 6 for a flow chart showing the process ofproducing a pattern in accordance with the present invention.

First, the method proceeds with step S71: placing a die inside aelectromagnetic actuator.

In one of the embodiments, walls of the die comprise at least onepatterned surface with a pattern formed thereon. The dimension of thepattern ranges from 1 μm to 10 mm, but the present invention is notlimited only to this specification. In one of the embodiments, theelectromagnetic actuator is made of an electromagnetic coil.

Please note that in step S71, the electromagnetic actuator can also beplaced inside the tube-shaped die, depending on the design ormanufacturing requirements of the pattern.

The next step in the process is step S72: disposing a tubular work piecebetween the die and the electromagnetic actuator such that walls of thetubular work piece correspond to the walls of the die and a formingsurface of the tubular work piece corresponds to a patterned surface ofthe die.

In one of the embodiments, the cross-sectional shape of the tubular workpiece can be rectangular, circular, triangular or other polygons. Thecross-sectional shape of the tubular work piece can be either the sameor different from the cross-sectional shape of the die. The thickness ofthe walls of the tubular work piece lies between 0.1 mm and 0.4 mm, butthe present invention is not limited only to this thickness. The tubularwork piece can be made of a metal or a compound material which has amagnetic conducting property. However, the present invention is notlimited only to these materials. Any materials, which can induce eddycurrents when the electromagnetic actuator is supplied with a current,are said to fall within the scope of the present invention.

In one preferred embodiment, the material of the tubular work piece issubstantially selected from aluminum, copper, ferrum, aurum, silver,titanium or any alloy combination thereof.

The process continues with step S73: placing a magnetic concentratorbetween the tubular work piece and the electromagnetic actuator.

In one of the embodiments, the magnetic concentrator is made of copper,but the present invention is not limited only to this material. Themagnetic concentrator can also be made of other conducting materials.Please note that the design of the tubular work piece and theelectromagnetic actuator can also be completed without the magneticconcentrator, and that step S73 can be skipped under this scenario.

The next step is step S74: supplying a current pulse to theelectromagnetic actuator to induce an eddy current in the tubular workpiece, thus generating a repulsive force between the electromagneticactuator and the tubular work piece. The repulsive force causes thewalls of the tubular work piece to impact on the walls of the die, thusdeforming the forming surface against the patterned surface to take onthe corresponding pattern of the patterned surface.

After the electromagnetic actuator is supplied with a current pulse, thecurrent passes through the electromagnetic actuator and generates amagnetic field. Simultaneously, an induced current is generated in thetubular work piece, and an opposite magnetic field is formed to repelagainst the initial magnetic field. The repelling field forces the wallsof the tubular work piece to impact to the patterned surface at a highvelocity, causing the forming surface to take on the pattern of thepatterned surface permanently. The pattern replicated on the formingsurface of the tubular work piece is formed at a high velocity by aquasi-hydrostatic pressure. Therefore, it has characteristics such ashigh malleability and fewer spring-back quantities and prevents creasesfrom forming.

The last step in the process is step S75: cutting the patterned formingsurface and separating it from the tubular work piece to form a plate.

In one of the embodiments, the die comprises the fracturing part, andthe fracturing part can be either an indented groove or a protrudingpart. After the electromagnetic actuator is supplied with a current, thetubular work piece impacts to the walls of the die at a high velocityand causes the tubular work piece to fracture at the positioncorresponding to the indented groove or the protruding part of thefracturing part. The patterned forming surface then breaks away from thetubular work piece to form a plate. However, the present invention isnot limited only to this cutting method. For example, any mechanicalcutting or laser cutting method of the prior arts can also be used toyield the same outcome.

Although the present invention has been explained in relation to itspreferred embodiments, it is also of vital importance to acknowledgethat many other possible modifications and variations can be madewithout departing from the spirit and scope of the invention ashereinafter claimed.

1. A method for producing a patterned plate from a tubular work piece,comprising: disposing the tubular work piece between a die and anelectromagnetic actuator, wherein walls of the tubular work piececorrespond to walls of the die and a forming surface of the tubular workpiece corresponds to a patterned surface of the die with the patternedsurface having a pattern formed thereon; supplying a current pulse tothe electromagnetic actuator to induce a current in the tubular workpiece, thus generating a repulsive force between the electromagneticactuator and the tubular work piece, wherein the repulsive force thencauses the walls of the tubular work piece to impact on the walls of thedie and deforms the forming surface against the corresponding patternedsurface to take on the pattern; and cutting the patterned formingsurface and separating the patterned forming surface from the tubularwork piece to form a plate.
 2. The method for producing a patternedplate as claimed in claim 1, further comprising placing the die insidethe electromagnetic actuator before disposing the tubular work piecebetween the die and the electromagnetic actuator, wherein the walls ofthe die are annular shaped and the die is pillar-shaped.
 3. The methodfor producing a patterned plate as claimed in claim 1, furthercomprising placing the electromagnetic actuator inside the die beforedisposing the tubular work piece between the die and the electromagneticactuator, wherein the walls of the die are annular shaped and the die istube-shaped.
 4. The method for producing a patterned plate as claimed inclaim 1, further comprising placing a magnetic concentrator between thetubular work piece and the electromagnetic actuator before supplying thecurrent pulse to the electromagnetic actuator.
 5. The method forproducing a patterned plate as claimed in claim 1, wherein theelectromagnetic actuator is an electromagnetic coil.
 6. The method forproducing a patterned plate as claimed in claim 1, wherein the tubularwork piece is made of a metal or any compound material which has amagnetic conducting property.
 7. The method for producing a patternedplate as claimed in claim 1, wherein the material of the tubular workpiece is substantially selected from aluminum, copper, ferrum, aurum,silver, titanium or any alloy combination thereof.
 8. The method forproducing a patterned plate as claimed in claim 1, wherein the diecomprises a fracturing part; and wherein the tubular work piece isfractured at a position corresponding to the fracturing part when thewalls of the tubular work piece impact the walls of the die.
 9. Themethod for producing a patterned plate as claimed in claim 8, whereinthe fracturing part is an indented groove.
 10. The method for producinga patterned plate as claimed in claim 8, wherein the fracturing part isa protruding part.